The invention relates to a magnet coil system having a plurality of individually drivable individual coils for contactless movement of a magnetic body in a three-dimensional working space that is surrounded by surfaces defined in a rectangular x,y,z coordinate system. Such a magnet coil system is to be gathered from “IEEE Transactions on Magnetics”, Vol. 32, No. 2, March 1996, pages 320 to 328.
Use is made in medicine of endoscopes and catheters that are introduced via incisions or body orifices, and can be displaced in a longitudinal direction from outside and can thus be navigated only in one dimension. Light guides permit optical inspection, it being possible to use control wires to rotate an endoscope pipe and thus the viewing direction. It is possible thereby to construct devices for biopsies, in particular. However, the probes used in this case can be navigated only in limited fashion, particularly at branching points, and so contactless exertion of force from outside could be attended by an expansion of the field of application.
The publication mentioned at the beginning and U.S. Pat. No. 5,125,888 A disclose a magnet coil system for contactless magnetic control of a probe comprising six preferably superconducting individual coils which are arranged on the faces of a cube whose position is to be described mathematically in a rectangular x,y,z coordinate system. The aim of these coils is to produce variable field directions and field gradients, in order to guide and to move a catheter with magnetic material or magnetic implants for therapeutic purposes in a body, for example a human body, to be examined. However, it is not possible to achieve unrestricted navigational freedom of the magnetic body with the aid of a magnet coil system composed of six individual coils.
U.S. Pat. No. 6,241,671 describes a magnet coil system having three coils, while U.S. Pat. No. 6,529,751 B2 describes an arrangement of a few permanent magnets that are arranged rotatably about a patient and whose field can be influenced by magnetic diaphragms, and which can produce a magnetic wave for moving a magnetic probe.
Also known, furthermore, are magnet coil systems having rotatable permanent magnets for controlling magnetic catheters, in particular with radiographic monitoring.
This related art does not address methods for stabilizing position by feedback; it is assumed that in a manner prescribed by field direction and gradient a magnetic probe body always bears against an inner surface inside a body to be examined.
WO 96/03795 A1 describes a method having additional pulse coils with the aid of which a magnetic probe is to be moved in a stepwise fashion by accurately defined current pulses under computer control.
So called video capsules that serve for inspecting the digestive tract are also known, for example, from the Journal “Gatrointestinal Endoscopy”, Vol. 54, No. 1, pages 79 to 83. In this case, the video capsule is moved by the natural intestinal movement; that is to say the movements and viewing direction are entirely random.
DE 101 42 253 C1 describes a corresponding video capsule that is equipped with a bar magnet and with video and other intervention devices. An external magnet coil system is intended to exert forces on the bar magnet for the purpose of navigation. Mention is made of a freely suspended, so-called helicopter mode with external control by a 6D mouse, a feedback of the force via the mouse, and a positional feedback by a transponder. No details emerge from the document as regards the implementation of the corresponding magnet coil system and the operation of its individual coils.